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Good and Bad Bamboo

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Running Bamboo! How to Get Rid of this aggressive grower if you don't want it —or plant it safely if you do

Question. You once discussed using vinegar to kill bamboo. Can you provide this information again? I am desperately trying to kill the bamboo in my back yard.

---Dianne in Bowie, MD

Mike: I have a property that borders an apartment complex and want to block the view with some tall evergreen plants. I see bamboo used a lot around here, but I've also heard it called 'Damn-Boo', and am concerned about it spreading into unwanted areas. What do you think? And what variety of Bamboo would grow tall enough (20+ Ft) here? Thanks,

---Jim in Swarthmore, PA

Dear Mike: Several weeks ago I was talking with my 80 year old aunt in Westchester, New York, and she mentioned that her son had planted bamboo in his rose garden. I have seen it out of control in nearby yards, told her what a nightmare the stuff can become, and suggested my cousin read your columns on the subject. Well, instead she tore it all out without telling her son, who was angry to say the least. He said it was a special variety that does not spread that he had spent $118 on! (He did add that he knew of the problems with other types, as a friend had rented a backhoe to clear a bunch that had spread from a neighbors yard.) Are there really non-invasive varieties? And less expensive places to get them? (I am thinking of replacing his.) And what do you think about bamboo and roses?

---Sadly Sorry Sue!

Answer. Poor Sue! That's a tough way to learn Gardening Lesson #1: You can tell other people what you think all you want, but never pull up their plants. Or pants.

Anyway, yes; there are 'nice' ones. As our good friend Ric Venzie, bamboo curator at the famed Japanese House in Philadelphia's Fairmount Park has explained many times on the show, the wide, wide world of bamboo (there are around 2,000 different varieties; here are a few of Ric's favorites: http://www.whyy.org/91FM/ybyg/bamboo.html) can be broken down generally into two groups: Well Behaved and Godzillas of the Garden.

"Clumping bamboos" grow like ornamental grasses—in big clumps that don't 'run' like the invasive varieties. But they DON'T just sit there either. The clumps expand outward by a few inches to a few feet every year, depending on the variety—and the soil and climate they're growing in. So 'yes' to some, but 'no' to others amidst roses. (Actually, 'no' to me, period. I think these plants look best displayed as 'specimens', all on their own.) The best-known clumpers for the Northeast are often referred to simply as the "Fargesias" (often whether they technically are or not). And yes, Ric assures me, clumping bamboos can be expensive. The source of this link is also one of the best overall websites about growing bamboo in the US: www.americanbamboo.org. Lots of great info there.

The ones that are always threatening to take over the world are known as 'running bamboos'. They spread by underground rhizomes, and CAN be safely planted inside restraints, but are perhaps the toughest invasive plants to eradicate when they are not.

Ned Jaquith, proprietor of "Bamboo Garden Nursery" in Portland, Oregon (www.bamboogarden.com) explains that the most accepted method of containment is to excavate a trench 30 inches deep and line it with "rhizome barrier", a heavy plastic sheeting designed to control aggressive plants. Most are 40 mil thick, but Ned had a 60-mil product made especially for his nursery (he estimates that 60 mil is about one-twentieth of an inch).

The pieces must be clamped together with special metal straps and bolts, the side facing the bamboo should be angled so that the roots are always deflected up (if its leaning the wrong way, the roots canget under the barrier, especially in loose fertile soil), there should be a lip above ground, and you should always be pruning back any culms that come up right next to the barrier. And that's just the short take—here's a link to more detailed containment directions from Ned's excellent website: http://www.bamboogarden.com/barrier.htm. (Note: Just about any specialized bamboo nursery will carry rhizome barrier and fasteners, and—perhaps most important—be able to recommend professionals to do the actual work. I get tired just thinking aboutit!)

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You can also contain running bamboo with a steam or other form of water that does not include a liner (they'll sneak under it). A wide, deep ditch filled with gravel will also stop them, as will a real road—but they'll sneak under a typical asphalt driveway. You could also pour concrete. "Bamboo Ric" Venzie and I have often discussed using sheet metal or corrugated roofing plastic as a kind of Cowboy Rhizome Barrier, but Ned and Ric both warn that the pieces would have to be fastened together perfectly to prevent the rhizomes from sneaking through.

Properly contained, however, running bamboo makes a perfect privacy screen. "Arrow bamboo" (Pseudosasa Japonica) is the one most commonly used in the Northeast; it grows to be around 20 feet tall, is thick and dense, looks great all year long—and believe it or not, is less aggressive than many other running types. (God help us all.) Variety choices vary greatly with climate—find a source close to you and ask their advice.

Eradicating running bamboo is tough. Take a good look at that advancing grove—it's actually one big plant, all growing out of one giant rhizome. The backhoe option is a good one; use it to remove every blessed piece of rhizome, which of course you won't be able to do. But any new culms that sprout up from rhizome shreds will be individuals; you should be able to dig these little orphans up and be done. But be warned; if it's coming over from a neighbor, you'll still need a rhizome barrier to stop future incursions.

If you have the patience, Ric and many others report success starving the roots. Cut the entire grove to the ground, preferably beginning in the Spring, when the rhizome has the least inherent energy. Let it re-grow until leaves appear on the culms, then cut it again. And again…. Producing culms takes a lot of energy out of that big honkin' rhizome underground, but the culms can't collect solar energy to feed it—only leaves can. Ric says you'll see each successive run getting weaker, until finally, what he calls 'the last gasp' will appear—a final desperate spurt of growth that looks more like zoysia grass than bamboo. That's the time to soak the area with a 20% vinegar or other intense non-chemical herbicide (see last week's Q of the Week for all the details) and finish it off. Ric says he's been able to eradicate groves this way in 3 or 4 years. If that's too long for you, I got two words: "backhoe". OK—its actually one word. Stickler.